Chain saw blade



March 15, 1960 c. I. FORS 2,928,440

CHAIN SAW BLADE Filed May 10, 1957 IN V EN TOR.

Carl 1 Fors any. 10 wax m AT TORJVEY CHAIN SAW BLADE Carl L Fors, Seattle, Wash. Application May 10, 1957, Serial No. 658,411 4 Claims. or. 143-135 My invention relates to chain saw blades and the general objects of my invention are to render chain saws safer to use and to increase the efiiciency and durability of the link type blades used in these saws.

One man power driven chain saws are extensively used in felling and cutting up timber. In cutting through logs or pieces of timber of substantial diameter or size with these saws the cutting is done by the lower lap of the chain saw blade, that is the lap which is moving toward the operator and is lowermost when cutting horizontal pieces. During the latter portion of a cut through a piece of timber of substantial size the lap of the blade which is normally uppermost andwhich is moving away from the operator is traveling through the cut or kerf made by the lower lap of the blade. Under these circumstances it is possible for the cutting teeth or links of the upper lap of said blade to gouge or dig into the walls of the saw kerf and kick or drive the saw toward and against the operator. This can, and sometimes does severely injure the operator.

An object of my invention is to provide a chain saw blade having teeth shaped and arranged and constructed in such a manner as to prevent them from gouging or digging into the walls of a saw kerf through which the idling lap of the blade is traveling and driving the saw back against an operator with possible injury to the operator.

Ordinary chain saw blades usually havetheir cutting links or teeth positioned alternately on opposite sides of the chain which forms the blade and each cutting link has a cutting edge on its outer side and on its tip. These saws have a tendency to whip from side to side as they enter the saw cut, due to the alternate oli-center positioning of the cutting edges of the links by which the cutting is done. greater when a cut is being started and the whipping often results in the kerf being much wider at the location where it enters the wood than it is deeper in the cut. This sidewise or lateral whipping of the chain saw blade is objectionable because it subjects the blade to side strain and produces a ragged cut, especially at the location where the saw cut is started.

Another object of this invention is to provide a chain saw blade in which all of the cutting links are positioned in the medial plane of the blade and in which each cutting link cuts substantially an equal amount on each side or" the medial plane of the blade thereby substantially eliminating the tendency of the chain to whip in sidewise directions, making it possible to reduce the thickness of the blade so that a saving in power results, and providing smoother and more efiicient operation of the saw.

Another object of my invention is to provide a chain saw blade which has a guard tooth positioned a short distance in advance of each cutting link and in which the guard teeth operate to prevent the cutting links from gouging into the walls of a saw kerf and thus prevent This tendency to whip from side to side is rates Patent 2.x the saw from being kicked or driven back against the operator. Y

Other objects of my invention will be apparent from the following description and accompanying drawings.

Figure 1 is an edge view showing the cutting edge of a chain saw blade constructed in accordance with my invention, only a fragment of the blade being shown and it being understood thatsaid blade is of endless construction and of any desired length.

Fig. 2is a side elevation of the blade section shown in Fig. 1.

Fig. 3 is a view partly in section and partly in elevation taken on broken line 3- 3 of Fig. 2.

Fig. 4 is a detached side elevational view of a cutting link of slightly modified form in that it is made of metal which is convergently tapered from the cutting edge rearwardly and the outer portion of the cutting element is slightly curved.

Fig. 5 is a view in side elevation of a cutting link of modified form made by doubling a piece of thin metal and leaving a rounded loop along the folded edge thereof to provide a cutting element, fragments of connector links being shown by dotted lines.

Fig. 6 is a view partly in cross section and partly in elevation taken substantially on broken line 66 of Fig. 5.

Fig. 7 is an edge view showing the cutting edge of a section of a chain saw blade of modified form embodying my invention.

Fig. 8 is a side elevation of the blade shown in Fig. 7.

Fig. 9 is a sectional view looking in the direction of broken line 9-9 of Fig. 8, parts being shown in elevation.

Fig. 10 is an edge view of another blade of modified form.

The form of chain saw blade shown in Figs. 1 to 3 comprises cutting links 10 and connector links 11 and 12 all pivotally connected together by pivots 19. The cutting links 10 are disposed in the medial plane of the blade and have connector links 11 on both sides thereof. The connector links 11 and 12 are of conventional form. The links 11 are provided with sprocket tooth receiving notches 13. The connector links 12 are in the medial plane of the blade and alternate with cutting links 10 and each link 12 has a guide fin 14 on its inner edge. The cutting links 10 have similar guide fins 15 on their inner edges and the guide fins 14 and 15 run in suitable grooves in the edge of a frame part of well known form, not shown.

Patented Mar. 15, l960 The outer edge of each cutting link 10 is bent circularly to form thereon an integral tubular cutting element 16 of generally cylindrical shape which is slightly larger in diameter at one end, namely the one herein referred to as the leading end, than it is at the other or trailing end. The convergent taper of the cutting elements 16 toward their trailing ends provides needed clearance and minimizes friction and wedging of these parts in the saw kerf. The cutting element 16 is sharpened at its larger end by providing within said larger end an internal bevel 17. This bevel 17 forms a cutting edge 18 on the leading end of the cutting element 16. Also the leading end of the cutting element 16 is biased so that V J an exitcopening 21. for sawdust or cuttings, said opening 21 being of expanding shape from leading toward trailing end of the cutting element;

A'fia'nge o'r. tooth 22; 'which' functions as a: gauge to limit depth of cut, is provided on each cutting link 10 in advance of andrin 'spacedfrelation from the leading end of the cutting-element 16 or said link. I The cutting edge of each cutting element .16 is arcuate andsymmetrical relative to the medial plane of the blade and cuts an equal amount on each side of the medial plane of the blade;so. that. loads and strains are evenly balanced and side deflection and 'whippingpf ttheibladeis substantially doneaway with. Also; making the cutting elements '16 symmetrical relative to the medial plane of theblade' substantially eliminatesiall 'tendencyof the cutting links of the idling lap" of. the chain" saw" blade to dig into or snag on the sidewalls-of the saw kerf through which they are idly moving and this substantially does away with the ,danger of kick back 'of thesaw.

Thecutting link 10? shown in Fi 4 is similar to, the link 10, just described, except that the metal of at least the cutting element 16' of this link is of convergently tapered thickness from leading to trailing end andthe outer part of the element 16 is curved inwardly to pro-.

vide improved tooth clearance and Vtohdirect sawdust inwardly toward the blade. Parts 15, 17, 18, and-22 of Fig. 4 are similar to the previously described parts 15, 17, 18, and 2 2', and function in a similar manner,

Figs. and. 6 show acutting link 23 which is similar in" shape andconfiguration to the previously described link but is fo'rmedby doubling a pieceofgthin metal adjacent cutting links 30 from digging or biting deeply plane" of, the blade! the lateral cutting edge.36 of the next cutting link rearwardly therefrom. The connector links 31 are made right and left and are used alternately on opposite sides of the blade. The connector links 31' are similar to the connector links 31 except that they are not provided with any guardteeth correspondingto guard teeth 39.

are'the same as the previously The guide links 32 I described guide links 12 shown in Figs. 1 and :2 but all of the medial links'of the blade shown in Figs. 7, s and 9 are guide links 3 2 wherea s. in Figs. l and 2 the guide links 12'are alternated with cutting links 10.

when the savv blade shown in Figs. -7,- 8 and 9 is to the side walls of said saw kerf and will prevent the into the side walls of'said-saw kerf and this substantially eliminates the danger of kick back of the saw and the possibility of injuring the operator in this manner.

Itis to'be'not'ed that in the construction shown in Figs. 7, 8 and 9 each cutting tooth has one side cutting edge 36 which is positioned to oneside of the medial plane of the blade. r

Thus in this construe on the cutting edge-of each cutting link is non-symmetrical as respects the medial In thecon'structions disclosed in Figs.- 1" to 6 inclusive the cutting edges are substantially in such a manner as to leave an integral tubdlaecutting element 24 on the outer edge thereof, The leading end f this c i e e lic es; lies-l e v ut e .5 l to. t prc euslrde s i sd s ti yeda 18: An exit opening 26 for sawdust is" provided in at least one d f wart n emen .4 a hs=.tr i. f ln th of; The cutting links 23 are each provided with a guide fin 27'and agauge tooth 2 8 which arerespectiyely similar to thepreviously described parts 14 and 22 of the'cutt ing isls i Th s tt sl nk 2 madsf t a i ef an are us ed alternately in the chain saw blade in the s ne rnanner as the previously describedcutting links links 23 function in substantially the same nne as t new i Y, j.

' Figs. 7, 8 and 9 illustrate a forrn of my invention in which all of the parts of a e hain saw isna sreereaaventional eon s tr uction exceptthat one conneetor'linkln a v e 1 thsls in ds i e tt n nl'i i vided with an outwardly protruding inclined guard tooth which will prevent the cutting edge of" then'eirt adjacent'cutting tooth t'o'the V rearfrom gouging. ordigging'into the side walls of the 7, s an 9 show s n te. saw blade made near cutting links 30, connector'links 31 andl 31 and guide links 32, all 'pivotally connected 'tog thr .in'chain form by pivot members cutting 1ia1 so*a re of conventional IR I I I right 'and left'for alternate use the saw blade Sai d e I ir'ig linksi30 each have atransversetyj offset integrat. cutting element Ea'cIi cuttih element 35 is wider a "its leading'end andta'pers rear is n her 'bf H l f Lw tins' inclined cutting edge 37 I provided wardly and e reagj edge 36 and an outer thereon; The inne edge of each c utting ;1ink30 has af sprocket tooth receiving 38 -the rein and pro; vide'dwitha tp thzs tjto gauge the depth or cut; The cutting links 30* and connector; links 3'1 are used I as ou tside {links and'tlieguide'links: 32: are-used as: rnedi'al-links I inr fbnning tneiblade; A c'onrrcetbrilink'3liadjacent the leadinge'nd ofithe cuttin'gelement 35 of each'link 3 0' is; provided with arr-outwardly protruding guard to'o th 'gi firnhich pu wardly ccnsid edgis,ing eds dcwi e away I "tr m t rns iairlanabfxthc g adesstbat thetipi or. s ster.

end ofeach guard tooth 39 is'approxirnately in line with blade shown' in Figs. 1, .2.and' 3.

saw blade constructionin which theflconnectorlinks 12 and cutting inh ler-havin parts '16.

kick back of the saw by preyenting V symmetrical as respects. the medial plane of the blade and there is a cutting edge on each cutting tooth on each side-of the medial plane of the blade.

' Fig. 10 illustrates the use of guard teeth similar to the guard" teeth 39' in a saw blade which is similar to the .Said Fig. 10 shows a and 18 are the same asthoseshoivniih Figs: .1.'. 2 and 3 and are similarly numbered. Eachrconnector link; 31 a shown in Fig. 10 has on its outer edge a guard tooth 39 which extends outwardly and isinclined away from the medial plane of the t blade and is similar to the guard teeth 39 of Figs; 7 and 8 except that it is" positionedapproximately mid way between the'two'endsof the link. The connector links 31a witli guardians: 39 are used in pairs thus providing two guard. teeth 39 in advance of each cutting link 10. This isfde'sirable because ,each cutting link 10 has a cutting edge on eachtside of the medial plane of the blade. The uar ans-39 operate, i a' manne similar to the uard; teeth ret eatin i kba k O e viously Lthfi .m s. fil'zi' having the medially positioned guardlteeth-39,"ca'ri'beused in placeof thelinks 31 in Figs. 7' and 8 construction. P-referably the corners of slightly rounded.

@The foregoing de cription-1th; rcjjctnpnyn drawings clearly disclo'se preferred embod ments of my invention a but it will beiunderstoo dthat these disclosures are merely illustrative and; that changes may be scope of the followingcl'aimsr- I claim:'. I ,I I II; I I I 1, In an endless chainsaw blade, a plurality of cuttmg made within the links positioned; in; a conamonplane; a plurality of connectorlinkspositioned alongside of said cutting links and pivotally connected therewith, the cutting-links being in the I medial plane ofthe bladerand an integral tubular cutting element prpv ided on the outer edge of each cutting llnk,

one edge pprtion of II a ch cutting element: being integrally 1 united withits-cuttinglink and each cutting element being of generally yliridrical shape and slighlty less than a complete cylinder :in cross section leaving a discharge r minaledge of each cutting t o fi'ts cutting" link and each at one end than it is at the end-and terr nin a ting i at l its larger end in a cutting.

or equal cutting on each side of the medial plane of dge yvhiehfis hisected h yV th e medial plane of the blade the blade, said cutting links being capable of moving smoothly through their own saw kerf without gouging engagement with the walls or" said kerf.

2. In an endless chain saw blade, a plurality of cutting links positioned in a common plane; a plurality ofconnector links positioned alongside of said cutting links and pivotally connected therewith so that the cutting links are in the medial plane of the blade; and an integrally formed tubular cutting element provided on the outer edge of each cutting link, one edge portion of each cutting element being integrally united with its cutting link, each cutting element being generally cylindrical in shape and slightly less than a complete cylinder in cross section, the other edge portion of each cutting element being spaced from the adjacent part of its cutting link and being inclined recedingly from the leading toward the trailing end of its cutting link leaving an expanding discharge slot for cuttings between said recedingly inclined edge portion and the adjacent part of its cutting link and each cutting element being larger at one end than it is at the other end and terminating at its larger end in a cutting edge which extends sidewise an equal distance from each side of the medial plane of the blade and which is inclined relative to a plane transverse to the plane of the blade, whereby said cutting edge will make a slicing cut as the blade is moved lengthwise through wood.

3. In a endless chain saw blade, a plurality of cutting links positioned in a common plane; a plurality of guide links alternating with said cutting links and positioned in the same plane as said cutting links; a plurality of connector links positioned alongside of said cutting links and said guide links and pivotally connected therewith so that the cutting links and guide links are in the medial plane of the blade; an integrally formed tubular cutting element provided on the outer edge of each cutting link, one edge 3 portion of each cutting element being integrally united With its cutting link and each cutting element being of generally cylindrical shape and slightly less than a complete cylinder in cross section leaving a discharge slot for cuttings between the terminal edge of each cutting element and the adjacent part of its cutting link and each cutting element terminating at one end in a cutting edge which is diagonal to and bisected by the medial plane of the blade, whereby it will cut equal amounts on each side of the medial plane of said blade; and at least one outwardly and laterally extending guard tooth on a connector link next in advance of each cutting link, each tooth having a terminal part offset sidewise from the medial plane of the blade a distance slightly less than the maximum transverse oliset of the cutting element of the adjacent cutting link, whereby said guard tooth prevents snagging of the cutting element on the wall of a saw kerf. a

4. In an endless chain saw blade, a plurality of cutting links positioned in a common plane; a plurality of guide links alternating with said cutting links and positioned in a common plane with said cutting links; a pluralty of connector links positioned in pairs alongside of said cutting links and said guide links and pivotally connected therewith so that the cutting links and guide links are in the medial plane of the blade; an integrally formed cutting element provided on the outer edge of each cutting link, one edge portion of each cutting element being integrally united with its cutting link and each cutting element being of generally cylindrical shape and slightly less than a complete cylinder in cross section leaving a discharge slot for cuttings between the terminal edge of each cutting element and the adjacent part of its cutting link and each cutting element terminating at one end in a cutting edge which is diagonal to and bisected by the medial plane of the blade, whereby it will cut equal amounts on each side of the medial plane of the blade;

and an outwardly and laterally extending guard tooth provided medially of the length of each connector, link, whereby two aligned divergent guard teeth are provided in advance of each cutting tooth, each guard tooth having its terminal part offset sidewise from the medial plane of the blade a distance slightly less than the maximum transverse offset of the cutting element of the'adjacent cutting link, said guard teeth preventing snagging of the adjacent cutting elements in the wall of a saw kerf.

References Cited in the file of this patent UNITED STATES PATENTS 2,534,591 Geurian Dec. 19; 1950 2,558,678 Garrett June 26, 1951 2,658,537 Ackley Nov. 10, 1953 2,713,276 Siverson July 19, 1955 2,736,352 Wright Feb. 28, 1956 2,747,623 Cox May 29, 1956 FOREIGN PATENTS r 185,564 Austria May 11, 1956 

